Number of inhabitants: 22,000 A short history : It has always been inhabited throughout history. It was first mentioned in 1247, when a document referred to a church dedicated to Szent Márton or St Martin. This church must have stood somewhere in the park of the present mansion house. Around 1235, Keszthely was given to István Lackfi, who started a ambitious building programme. It was he who had the Gothic church standing in the present main square and the Franciscan monastery built. In the 15th century Keszthely, with approximately 1000 inhabitants, was the biggest market town in the area.

Its owners changed from time to time. From 1430 to 1739 one of the most prominent families of Western Transdanubia, the Gersei Pető family owned it. Their mansion was in the place of the present mansion house. In the middle of the 16^th century, János Pető had the church and the monastery surrounded by a palisade and fortified bastions following the plans of Italian military engineers. Its defenders successfully faced the renewed Turkish attacks, and though the Turks stormed the town several times, they never managed to take the castle. During the Turkish occupation, the inhabitants of Keszthely served as soldiers as well, so they were freed from statute labour. The provision of the food and general supplies was the duty of another settlement, which was not freed from such duties. This settlement was called Keszthely "civic town", later Kiskeszthely, which is now merged with the main town of Keszthely.

In 1739, the Keszthely lands of János Pető were bought for 24,000 forints, then an enormous sum, by the Festetics family, who later played a key role in the life of the town. Kristóf Festetics organised his huge estate during nearly five decades of meticulous work, not without any manipulation, either. He transformed it into a unified domain and made it the centre of all his estates. In the place of the former Gersei Pető mansion, in 1715 he started building his mansion house, which reflected the wealth and power of the Festetics family. The mansion house was later extended by the descendants.

In 1772, Maria Teresa made Pál Festetics count. The decades to follow had a lasting impact on the life of the town. In 1772, a grammar school was established, which later was given the building of the Franciscan monastery. In 1808, the school was taken over by the teaching order of the Premonstrants, who ran it till it came under state control. In 1797, György Festetics founded Georgikon, the first agricultural college in Europe. He also organised the Helikon Festival with the aim of promoting the sciences and the Hungarian language. At these festivals, Dániel Berzsenyi, Sándor Kisfaludy, and Ádám Pálóczi Horváth also appeared. The town owes a lot to the development of transport. The first steam boat came into Keszthely harbour in 1846. At the turn of the century, a branch line connected the town to the southern railway line. The Balaton, called " Eden a hundred times over", attracted tourists even in the middle of the last century, bur regular tourism started only in the 1860's. At the turn of the century, the Balaton shore was developed. A new port for steam boats was built in 1891, followed by the building of the Hullám restaurant and the Hotel Balaton. In 1898, the Balaton Museum was founded. Keszthely became a fully recognised town in 1954 .